Observation and uses of position-space Bloch oscillations in an ultracold gas

TL;DR

This paper reports the direct observation of position-space Bloch oscillations in an ultracold gas within an optical lattice, enabling new insights into quantum dynamics and potential applications in quantum control and measurement.

Contribution

It demonstrates the first direct measurement of real-space Bloch oscillations and introduces techniques for imaging band structure and phase-space evolution.

Findings

Observed real-space Bloch oscillations over hundreds of lattice sites

Enabled measurement of full phase-space evolution during a Bloch cycle

Achieved direct imaging of lattice band structure

Abstract

We report the direct observation and characterization of position-space Bloch oscillations using an ultracold gas in a tilted optical lattice. While Bloch oscillations in momentum space are a common feature of optical lattice experiments, the real-space center-of-mass dynamics are typically too small to resolve. Tuning into the regime of rapid tunneling and weak force, we observe real-space Bloch oscillation amplitudes of hundreds of lattice sites, in both ground and excited bands. We demonstrate two unique capabilities enabled by tracking of Bloch dynamics in position space: measurement of the full position-momentum phase-space evolution during a Bloch cycle, and direct imaging of the lattice band structure. These techniques, along with the ability to exert long-distance coherent control of quantum gases without modulation, may open up new possibilities for quantum control and metrology.